Workflows developed to process pollen data to estimate components of ecosystem change

PAGES Planetary Boundaries Working Group

• Holocene variability is a key component of planetary boundaries concept
• Focus on temporal dynamics/ safe operating spaces
• “To meet the challenge of maintaining the Holocene state, we propose a framework based on ‘planetary boundaries’. These boundaries define the safe operating space for humanity with respect to the Earth system and are associated with the planet’s biophysical subsystems or processes.” Steffen et al. 2009

Introduction

Example from pollen data

• Focus on temporal dynamics
• We need a metric (or series of metrics that can reflect something related to the planetary boundary)
• We need a method for describing the variability (e.g. using a generalised additive model)
• If we are talking global planetary boundaries, we need to look at multiple records, so need a reproducible method to show how to do this.

Diversity metrics

GAMs

• Statistical model to show non-linear trends through time
• Gavin Simpson has done the groundwork to transfer this method to palaeoecological data (Simpson 2018, Presentation on Wednesday, 11-11.15)
• Models a trend (e.g. diversity against time) using a series of basis functions, allowing non-linear trends to be fit to data

GAMs

• ‘Generalised’ framework means it is highly flexible, used on multiple data types
• Note that it doesn’t necessarily tell us where we should draw the boundary, but it does give us a statistically robust description of the variability which we can then use to make informed decisions

GAMs

Reproducible workflows

• If integrating across multiple sites then it is important to have standardized data that are comparable
• In pollen this means- same depositional environment, same age-depth models, same levels of taxonomic harmonisation, (same/ similar temporal resolution), comparable temporal ranges etc.
• We have been developing reproducible workflows for pollen data in the HOPE project, we will show an example of this today (see Ondrej’s poster)

Reproducible workflows

Aims of this practical exercise

1. Give an example data preparation and analysis of one metric related to the Biodiversity Planetary Boundary from a set of pollen counts from Lingua d’Oca (ID = 52162) record by Feredico Di Rita.
2. Give hands-on practice of applying the code to other examples (e.g. downloaded from Neotoma)
3. Stimulate some discussion points related to the types of metrics/ standardization procedures that are relevant for your data and for the Planetary Boundaries’ concepts

Practical exercise

Go to bit.ly/INQUA2023-PBW

Example: Global changes in rates of vegetation change

Wrap up

• Used this one example of how to process the pollen data in standardized methodology
• See the whole workflow which enables you to do this on Neotoma and other datasets (FossilPol).
• Interpretation of results in relation to the Planetary Boundaries would be open ended, and is the focus of the group and for discussion here.

Discussion points

• Here we focused on temporal dynamics, but how can we get from response to control variables?
• What other metrics/ ecosystem components could be used on pollen data? What about other proxy types
• What would be the challenges of doing large syntheses in the context of the planetary boundaries for your data types?

Discussion points